No abstract

Teak plantations cover a total area of about 4.35 million ha worldwide. The species is currently being planted in silvopastoral systems in the coastal lowlands of Ecuador. However, there are no growth and yield models for teak grown in silvopastoral systems, especially as living fences, in this region. The aim of the present study was to develop volume and yield models for teak grown as living fences in silvopastoral systems. For teak planted as living fences, the biological rotation age was estimated to vary between 15 and 26 years. The final yield in the silvopastoral system varied from 49 m 3 ha −1 at 26 years in the least productive sites to 225 m 3 ha −1 at 15 years in the most productive sites in the study area. The mean annual yield for the highest quality site was 15.3 m 3 ha −1 year −1 at age 15 years, for a density of 160 trees ha −1 . For a base age of 10 years, height-based site indexes of nine to 23 m were established. The growth and yield model obtained may be useful to define the biological (optimal) rotation age and estimate the productivity of teak living fences in the coastal lowlands of Ecuador.

In this study, we examined the spatial genetic structure (SGS) in extensively managed, but naturally regenerated forest stands of Pinus cembroides Zucc., Pinus discolor Bailey et Hawksworth, Pinus durangensis Martínez, and Pinus teocote Schiede ex Schltdl. & Cham. at local (within the stands) and large (among the stands) scales using amplified fragment length polymorphisms (AFLP), with respect to conservation and sustainable management of genetic resources of these species. Because these four pine species grow in different landscape structures, we expected to find differences in their SGS, although all of them are widely spread, wind pollinated, and often occur at high population densities. At the local scale, there was no evidence of significant SGS in the four species under study (except in 1 out of 18 seed stands), suggesting that the genetic variants of these species are almost always randomly distributed in space, probably due to high wind pollination and seed dispersal. At a larger scale, the significant SGS found may be the result of isolation by distance among populations. We recommend (i) establishing a tight network of seed stands, with a maximum distance of 3–11 km between seed stands, to prevent greater loss of local genetic structure, and (ii) using these seeds to establish reforestations within a maximal radius of 3–5 km from seed provenances.

Objetivo. Evaluar la viabilidad económica y financiera de los sistemas silvopastoriles tradicionales para la producción de Biocombustibles como aporte a la sostenibilidad del proyecto “Piñón para Galápagos”. Materiales y Métodos. Se llevaron a cabo encuestas a 450 pequeños productores ganaderos de 10 cantones de la provincia de Manabí con la finalidad de colectar información agronómica, manejo, costos implicados en establecimiento y producción de los sistemas silvopastoriles vigentes de Piñón (Jatropha curcas L.)/Saboya (Megathyrsus maximus). Para recopilar datos de producción del Piñón establecido en cercas vivas de Piñón INIAP CP041 e igualmente se registró la producción de sistemas en 10 sitios, desde el año 2009. Con estos datos se calcularon los siguientes indicadores financieros radio beneficio/costo (B/C), valor actual neto (VAN), tasa interna de retorno (TIR) y valor de expectativa de la tierra (VET). Resultados. El estudio mostró una disminución de la producción del Piñón con el transcurso del tiempo. El sistema silvopastoril mejorado con Piñón INIAP CP041 mostró B/C 1.07, VAN de USD$ 404.11, VET USD$ 970.23 y TIR de 18%. Seguido del sistema silvopastoril con Piñón local con un B/C 1.06, VAN de USD$ 363.66, VET USD$ 873.10 y TIR de 17% y finalmente sistema silvopastoril sin cosecha del Piñón con un B/C 1.05, VAN de USD$ 285.72, VET USD$ 685.99 y TIR de 15%. Conclusiones. La alternativa de producción de biocombustibles con sistemas silvopastoriles Piñón (INIAP CP041)/Saboya en Manabí es el sistema de mayor rentabilidad y no competiría por superficies de cultivo para la producción de alimentos, sin afectar a la seguridad alimentaria.